FORM studios Architecture planned the building as a mixed-type construction project, with one-half of the building constructed with wood for a one-story classroom built on a slab foundation, and the other half a taller steel structure with columns to support a wide-open area for the sanctuary. Each side would need a different treatment for the foundation to deliver the proper support.
The building site presented additional challenges. Geotechnical reports indicated the site contained very expansive soils with a high PVR (potential vertical rise), and the original plan was to use water and chemical injections with a pier-and-beam foundation to ensure stability. Yet the builder encountered a significant amount of water underground when the drilling began, indicating another approach would be necessary.
According to Jason Presley of FORM studios, the firm had worked with the same contractor when building the Spanish House Immersion School in Dallas the year before, and had success working with the Tella Firma Foundations solution, which elevates the foundation off the ground and away from the expansive soils. This time, Tella Firma helped create a hybrid approach for the Kingdom Life Christian Center, with lifting piers supporting the slab under the classroom and sanctuary sides of the structure, and non-lifting, cased piers supporting the steel columns only in the sanctuary. The team designed a pour strip in between the two sections of the building, and metal stud infill was utilized around the columns. The two sides of the foundation were lifted at different times.
Mr. Presley said the hybrid solution required a little more planning and preparation at the outset, but was well worth the effort in terms of saving money on construction. Beyond the savings realized based on the projected cost of a pier-and-beam foundation, the originally planned remediation of the soil would have increased both the time and cost of the project overall.
According to Mr. Presley, one of the most important considerations for this job was to have a good engineer who could assume responsibility for the design of the foundation around the steel grid. And the outcome demonstrates the benefit of looking at both sides of the equation.